Well, you could speak in terms of joules per second or hour, but it is not possible to speak in terms of watts per hour, or watts "per push", since a watt is a measure of energy conversion rate, like miles per hour. 1 watt = 1 joule/sec. Speaking of watts per hour is analogous to saying "miles per hour per second," and only could have meaning as a derivative, indicating a change in the rate of energy production.
The total amount of energy (in joules, watt hours, or calories) produced would depend on how long the person could keep up this (100W) rate of energy generation. Frankly, 100W sounds like a peak rate, and after several minutes of peddling this rate would probably begin to drop off rapidly as the person became exhausted.
He always picks on me, I'm just not sure what his issue is with me. Thats my frustration.
Yes you are correct jrf why watts isnt very descriptive. You can also convert joules into ft pounds.
Through gear reduction you increase torque and decrease rotational speed. If done in reverse, you increase speed and decrease torque. Simple engineering concept. This is the reason why I said mountain bike, since it has gears. If implemented with a flywheel, you could store much more kinetic energy than you could through hand rotation or no gear reductions. Flywheels can store massive amounts of kinetic energy. It will be harder through acceleration than keeping it at full speed.
I'm going to try a proof of concept. I just got back from Lowes and bought the heaviest 8" steel lawnmower wheel I could find, polycarbonate and some bolts and bushings. I have a tiny dc motor and a larger to serve as a generator, I'll repost if it generates more energy than required to keep the RPM up. Not sure, but I wanted to experiment, since I didn't know.
The small motor will run a belt around the 8" outside diameter of the wheel. The generator will be attached to the axis of rotation on the wheel. See what I can do. I don't know how long it will take to build, and I don't have specs off the motors if I need them to do the math for a larger system. Thats the crappy part. I could buy new motor with spec sheets and torque curves published. If real critical you need to know the weight of the rotor and any friction incurred from rotation, but you mostly only need that in closed loop motion control. I don't think it will be critcal issue with my setup, but who knows.
"Damnthematrix, what possible function can the first sentence of your latest post serve, other than to efficiently and effectively create bad feeling?"
Well, SPM's replies only proves that I am 100% right actually. If he is upset by what I have to say, and I do know what I'm talking about (I am an energy consultant after all), then it's his problem, not mine.
"you can get much more than 100 watts through your personal ability. Blatantly incorrect."
Well SPM, it is YOU who are blatantly incorrect:
The amount of electrical power that can be generated by the Human Power Generator is determined by the energy available to turn the crank . The stronger the user, the more electrical power can be produced. Typical output in watts with the Human Power Generator is about 60 Watts or 35 Watts with handcranks.
The typical average continuous power that can be generated by pedaling the Human Power Generator is up to about 80 watts. The maximum power obtainable through hand cranking typically is about 50 watts.
So you see, I'm being somewhat optimistic with my figures, though if you are really fit, I'm sure you could muster 100W. Your saying "Is it 100 watts per hour, or one push, 100 watts your arm is done for the day?" clearly shows you do not understand energy. Watts is POWER. ENERGY is POWER times TIME. So 100W per hour is 100Whr, over a whole day it would be 2400Whrs. One push would give you 100W for half a second at best. POWER is continuous, for as long as it is applied. The length of time the power is applied determines how much energy is generated.
If you are going to write up stuff about fairly complex issues like energy and energy conversions, it is a good idea to first understand the basics, otherwise you'll end up building things that will simply not work.......
I'm not trying to upstage you at all, I'm actually trying to HELP YOU.... and others who read these threads. If I come across someone who knows more than me on something, I listen to them and learn.....
You still negated gear ratios....... WaitingAnd if you factor that in with a flywheel Mr. Energy Consultant, I think you can do more than 80 watts. What if through the crank you did a 2:1, could you generate 160watts per second? It may be a complex concept to grasp, but I am not incorrect. Since your person is causing rotation and power generation, its false to say that you can only generate 80 watts through human power. Since I can prove a bicyle and a flywheel can generate more than 80 watts per second under human power. The limiting factor would be how large a diameter and weight of a flywheel you could obtain and mount safely. I know the math thank you, just jrf29 was nice, so I didnt feel the need to say anything.
I was doing fine ignoring you, I'm not sure why you felt you had address me directly today. I still read your posts, just no comment from my peanut gallery.
See...... you guys do NOT know what you are talking about!
1 Joule = 1 W sec. Please get your facts right if you're going to talk physics.
100W can EASILY be exceeded for short bursts by very fit cyclists. Lance Armstrong was once MEASURED putting out 800W..... but I'm sure you are no Lance Armstrong. Funny name for a cyclist hey, should've been called Lance Legstrong!
"Through gear reduction you increase torque and decrease rotational speed. If done in reverse, you increase speed and decrease torque. Simple engineering concept."
Which has NOTHING to do with energy..... All gearing does is allow you to go faster on a flat, or allow you to ride up a steep incline, but not BOTH at the SAME TIME!
You can do 25MPH on a flat @ 100W, or you can ride up a steep hill at walking pace with 100W. If your body can store enough energy to do this for 4 hours, then you will have used up 400Whrs to do 100 miles on a flat, or 25 miles up a dirty great hill.
ALL the gearing has allowed you to do is go further on the flat, and allow you to get up the hill which would have been impossible without the lower gear.
1 Joule = 1 W sec. Please get your facts right if you're going to talk physics.
And all these years I have been laboring under the tragic misapprehension that 1 watt = 1 joule/sec, and that 1 joule (a unit of energy) in turn loosely equals 1 newton meter, or 1/4 calorie. Did you say you are an energy consultant?
I would agree about the gearing, though.
Hehe, I think I'm out of this conversation. The only point of gears Mike is to increase the amount of kinetic energy you are capable of putting in the flywheel, thats all. If you tried to do it by hand crank, it would very difficult. Be more humble my friend.
Research flywheels Mike, it would be an important lesson for your energy cause, seriously. I need a roomate though, want to move to California? j/k
I think it could be workout to get the flywheel up to speed, but you would only have to supplement at intervals, versus constant pedaling. Higher speed, less torque. The flywheel depending on size can maintain massive amounts of energy. You can setup an alarm at a certain rpm so you don't have to pedal all the way from a dead stop.
I dont recall the RPM, but we had 75 ton with about a 4 to 5 foot diameter wheel. I think it was 5 or 10 hp motor though. 1750 or 3600 rpm, I can't remember now. The motor was reduced by small pulley on the motor, and belts directly around the large OD of the flywheel. Pretty cool stuff. Wouldn't want to get your hand caught in anything.
Dear oh dear..... this is really painful you know. The power in your legs is determined by your physique. And what sort of food you eat, and how much of it. End of story. It's just like a car. You can have a Ferrari, but it won't go anywhere without gas.
The power you put in at the crank is 100W, and what comes out at the wheel is still 100W (assuming 100% efficiency), all the gearing does is change the speed of the wheel. If you are in a high gear (and stay in it), you will soon be stopped by the first hill that comes along. If you are in a low gear (and stay in it), you will not be able to go fast EVEN if you could put out 1000W!!!!! because you simply will not be able to pedal fast enough.
If you can't understand any of this, I just have to give up on you I'm afraid.... you're making my brain hurt!
Oooops... you are right of course, I just got carried away in the heat of the moment and misread your equation. Sorry.
SPM, You saying "160 watts per second" ( and other subtle indications in your comments ) indicates to me that you may not "instinctively" understand energy relationships.
A person can generate well over 100w, but only for short duration. Mikes figure of 100w for sustained power sounds OK. I forget the precise numbers but check out about the guy who flew over the English channel in a human powered plane if you want to find out how much a REALLY fit person can manage for a decent period.
Crudely speaking a horse can generate 1 horsepower for a sustained period, strange coincidence or what ?? ;-) and 1 hp is 740W ( or there about )
However, on to your flywheel storage.
Some of the problems between you and mike look like they stem from they way you each explain and then interpret the others explanation, so I will have a wee go ( know so much of this "instinctively" but trying to explain it here.....argh.. English can be a shit for this but it is the only language I speak !!! )
Getting the flywheel up to speed takes a lot of energy. If it was running on frictionless bearings in a vacuum chamber etc, you would not need to put any effort in to maintain its speed if you were not drawing any power out.
Once you start to draw power out it will slow down.
The energy you could extract would be the amount that you put in. ( assuming no losses .... )
You could have put the energy in at 80w and extract it at 160 w, but for every minute of 80 w in you would only get 0.5 minute at 160 w, 0.25 minutes at 320 w or 2 minutes at 40 w( no losses accounted for )
A bicycle wheel would make a very poor flywheel, but using bicycle parts to spin up a big flywheel is achievable, but re read damthematrix post #21 about how much energy is available from leg power.
Big very heavy flywheels can store a reasonable amount of power, and for stationary low tech mass is the way to go.
Modern lightweight flywheel units are usually made from filament wound carbon fiber and spin at VERY high rpm. Carbon fiber as it has a very high tensile strength an low elasticity, and so can be spun to a much higher speed than a steel one, which would have torn itself apart via tensile failure at lower rpm.
High rpm are good if you want light weight as the energy stored = 1/2 M V^2, so doubling the rpm stores 4 times the energy, but doubling the mass only doubles the storage.
Not being a math whiz or an electrical engineer or a physics major or an expert of any kind, I'll propose that kinetic energy may be better stored and reclaimed via tension.
Purely conceptually, if you used your abundant but transient generated power (PV, wind, animal or human) to twist ropes or cables into high tension, then blocked the gear, you could then reclaim some portion of that energy at a later time when you release the block and tension. If you stored enough of this tension, it would be possible to convert it to electricity through a flywheel or other form of generator.
This would be akin to using a crank to tension a rope on a ballista or catapult that hurls a projectile with more force than you could do it in one go by hand (i.e. it allows you to capture, store and release each turn of the crank cumulatively). Except, in this case, you'd be capturing the "hurl" force and releasing it later to an electrical generator of some kind.
Studies of Medeival designs for seige ballistas and catapults indicate close to 100% efficiency of kinetic capture, storage and release... so we'd just need to figure out a way to capture this force to generate electricity when we need it. We'd need the capacity to use all (or most) of the kinetic energy over a longer duration than the initial release... perhaps this is where SPM's flywheel could come into play.
I suppose you could use some sort of counterweight, like trebuchets did, to turn your input into kinetic potential through gravity... but I suspect this would be even more lossy than tension because you're expending more initial energy to move the weight. Our current studies do indicate that the ballista and catapult were much more effective/efficient for their size than trebuchets and had much greater penetration. However, trebuchet's advantage seems to be that a heavier/larger projectile could be thrown. So, it appears that there is a difference in tension force and gravitation/counter force used between the two designs... and this difference may dictate which form of generator would work most effectively with each.
Thanks, Mike. That explanation (that all the power goes to the grid first) clears up some of it.
The batteries are certainly the weakness in RE. As we come down the backside of the peak, energy prices will shoot up, and there may likely be shortages. Demand for RE will shoot up, and batteries may become hard to get. It seems a shame that a system intended to be renewable depends on a non renewable element like batteries.
It makes me wonder how power is no managed on the commercial grid. What happens to extra power when it is not called for? I know it keeps getting distributed over a wide network, but there must be some extra somewhere. What I'm really driving at is the possibility of a local grid. There's got to be some way to generate usable power without replying on expendable batteries or FF supplied commercial grids.
I have an installed 3.5 kw PV system that is grid tied and runs a single meter backwards. I have had similar considerations as regards batteries, backup power and so on and wondered really how sustainable it is given the life of the batteries (I have heard +/- 5 yrs) and the panels (+/- 25 yrs).
That said, I think that a local grid is a better option and that is based solely on opinion at this time. We have a local commercial power generator which burns wood to create steam and run a turbine to create power. The waste wood is used to generate power and this comes from thinning that is needed to help reduce fire danger in our mismanaged forests. This plant has been operating for about 15yrs.
This is/was a logging and mining community and the original trackage and steam powered train and railroad beds are largely intact as is the original Shay #3 steam powered engine which is being completely refurbished at this time. So ultimately steam could be used to haul the waste wood and generate power much as it was pre-oil. The power plant can supply 100% of the needs of our county which has a population of just unter 60,000 so it would seem to me that we would be far better off enhancing a system like that rather than in developing individual systems.
I would assume that concentrating solar power systems would be more efficient to use to augment the source of steam on sunny days and reduce the demand on wood over the long haul. A system like this could be powered up or down depending upon the time of year and demand and eliminate the battery issue.
Getting our local politics wratcheted around to embrace this concept will be no doubt a tougher job!
You get what you pay for.
Industrial "forklift" style batteries have positive plates that are often 3 or 4 times thicker (mine are .290", most "PV" rated batteries are .090", deep cycle are even less) than what are being sold as PV or off-grid batteries.
If you properly design your system so you do not constantly deplete your batteries, maintain them, keep them at the right working temps, and have really thick positive plates, your batteries can last 15 - 20 years.
While this is not indefinite, I am guessing I, or someone else, will come up with a solution in the next 15 years. If not, I had 15 years to pack a parachute.
Traction batteries such as are in forklifts have very thick plates because they have to supply HUGE currents (500+ Amps), often in short busts.... forklifts never move very far, and then stop, and start again, etc.
Deep cycle batteries don't have such plates because that sort of load is not normally required in a RE system. What you will find though, is that Deep Cycle batteries have very large surface area plates, usually by being textured like a waffle, and because the batteries normally have large cross sectional areas. It's not unusual for a DCycle battery to be two feet tall.
I was always taught that the best batteries for deep discharge WERE DCycle batteries, and that the best batteries for vehicles WERE traction batteries. It's horses for courses. I've seen well designed stand alone system, by which I mean the load, solar array, wiring, inverter size, wiring protection, AND battery bank sizing has ALL been done correctly, have their batteries last twenty years...... and I'm talkinf about systems WITHOUT backup generators!!
I cannot overstate that if you want your system to work perfectly, it needs to be designed and installed perfectly as well. It is this bad design process that for a very long time now has given solar power a bad name with premature battery/inverter failures.
Hamish, I'm aware. My beef was saying all humans are capable of is 80w. That is a very misleading statement. A time relationship or other measurement needs to be added with it. This being said, I'm not here to prove I know anything mroe than the next guy, or take anything away that other members contribute. This is an area I have a little knowledge, so I am more than happy to post information, and I have a lot of ideas. I would appreciate though no more personal attacks, If I am wrong I will gladly admit it, but common courtesy would be nice, since I extend that to others. This information will be here potantially much longer than we will, so its nice if its accurate.
If someone can please provide a reliable cited source for power capable from humans, I would appreciate it. I'm also aware on flywheels, I read the same information as you, and have the same textbooks. You need magnetic bearings to be the most efficient. SKF makes some, not sure on the tremendous price though, says write for inquiry on their website. My whole statements were regarding a bicycle and a flywheel, not using the back tire of a bicycle as a flywheel. Read carefully please. If I am not clear enough on my intentions, I apologize, plus, I don't want to give my whole idea away. You have the basics. To sit down and do all the engineering and math will take a few days in its entirety, based off store bought parts, and what I can dig up in my garage. Right now, I am shooting off the top of my head.
You are putting energy into the flywheel, I agree with that, but the faster the flywheel spins, the less torque will be needed from you to keep its rotational force at maximum. Unless your load on the generator is huge. I don't know the specs for rotor resistance based on load off the top of my head. If the flywheel is large enough in diameter, it should be able to overcome a significant amount of load, more bearings and gears add more friction, this will be the problem I run into. Plus, where you input power, and where power is removed from the flywheel are two completely seperate locations with different factors of force. Your ability to keep the outer rim at maximum speed with the least amount of torque is much different than least amount of speed and maximum torque, at its axis. Same amount of energy though contained within the wheel. The onyl difference is you can release all your stored energy at one time, vesus a crank you are limited to the amount of torque and rpm you can put on the generator. So in theory, I could store an hours worth of energy, and release it all at one time, increasing my maximum one time human output. With a big enough flywheel, you could release hundreds of amps in a second or less, if that was your load. I understand what you guys are saying about maximum human intput into the wheel, but I just think its open to interpretation.
PlicketyCat: I like the idea of using spring coils and other ideas for storing kinetic energy.
I would like to see if large scale systems of weights, pulleys and pendulums would work such as those used by cuckoo and grandfather clocks. Anybody know of anything out there that already exists like ancient town hall clocks or something? Anybody want to weigh in?
Ruhh - Have you seen some of the gravity motors people have made? I have yet to come across a video of one working, mostly only plans and someone says it works. One guy who had a pretty good idea used a wheel with offset arms, and a weight and solenoid to throw the weight once it needed to be reset. If think if people can get those ideas working, and its heavy enough, it can generate a lot of electricity. I think you need good fail safes though, because I think things like that have the potential to spin themselves fast enough that they catastrophically fail. I did see one video where a guy used a like a 8 foot flywheel, I'm not sure if it employed gravity, or what he used to keep its rotation, or if it was even real, but it spun and ran a rather large generator. He didn't explain much, and I understand if it isn't patented, but a simple explanation would be nice.
The problem I see with those kinds of idea, even a flywheel as a replacement for batteries. The potential to catastrophically fail is too high, and as such need to be designed with these considerations. You would need full heavy steel and concrete enclosure for most of these ideas.
I dont particularly like the concept behind current magnetic bearings. They are supported by nothing other than the magnetism. If a coil or the driver fails, there is no mechanical connection to contain the flywheel. A mechancal that only engages if the magnets fail would be nice. Maybe you would have to that yourself. Would not be a pretty sight if that happens though.
With proper design a flywheel can be used to indefinately replace batteries. With RE power available you can use a motor to spin the flywheel and keep its amount of stored energy at maximum. Once its achieved the maximum amount of energy allowable, keeping that force will require much less energy. When RE power dissipates the amount of stored energy in the flywheel can slowly be released to supplement the energy needs. Proper design is critical, much more so than a battery system, but the fact that you will never have to replace it, only do minor maintenance far outweighs, to me, the use of toxic batteries.
Breakthrough in Hydrogen as Energy Source
I swore to myself that I was going to stay out of the bickering, completely steer clear of posts that have that potential. I just wanted you to know that I see nothing in your post that would illicit such a response.
You may not like the way this started with Mike, but the folks here seem to be trying to help you. Forgetting the gruff way Mike comes across (I know! I know!), he and the others here are trying to save you some time and money. You might want to take a deep breath and re-read from the beginning with an open mind. Skip the parts that made you mad and focus on the science.
I went to an exhibition a short time ago where one presenter had a 10 speed connected through gearing to a generator outputting to a 100W incandescent light bulb. After 3 minutes of keeping that bulb lit, I started to feel the sweat run down my back. I doubt I could have managed a half hour, let alone an hour. Honestly, even if I could the time would be better spent elsewhere on the farm and would have reduced the amount of food calories needed that day.
Before you object, take a few minutes to think it through. And please remember that this is not an attack, rather I, and others, are trying to help you. A flywheel nor gearing does not in any way magnify the energy a human can produce. They only convert it, at a loss. Assuming you are physically stellar and are able to keep a 150W bulb lit in first gear for hours at a time, switching into second gear does not produce the power needed to light 2 150 watt bulbs. You have to grasp this in order to move forward with your projects and obtain the success you seek and deserve.
The principals im refering too are dealing with mechanical engineering, not electrical, I'm not debating anyone on the electrical aspects. Only that if that bicycle were attached to a flywheel, your input and power output would be different, thats all. I would make an honest bet that more than 100 watts would be possible. However for the consumer market, a few hundred pound wheel spinning at 1000 rpm, a few feet behind you, isnt the safest thing to do. Flywheels have been used in mobile applications, but the gyroscopic effect of the spinning wheel is too great. The weak link is the gimble systems, one failure you're done.
Sorry, wrong link. Its the correct company but referring to there hydrogen technology. Go to Coors-tek.com They are the parent company and look at the ceramatec battery they have developed.
I thought the one article you linked was very interesting. I don't know much about that stuff, but sounds like the way to go. The hydrogen atom is much larger than the oxygen atoms. I think you could effectively seperate them with a permiable membrane. Similar to an RO filter, but much smaller holes. I think the energy is going to be consumed in forcing the atoms through the membrane.
Is it possible for the total energy output of any system to exceed the amount of energy put in?
Nope. But the difference is at one time or over a constant. Also the difference is based on human input at the od and power produced from the axis. In the 21st speed, not much torque, only speed. The more mass in the wheel, the more resistance it can overcome from its axis, and retain more energy. As long as you can keep it in the 21st speed, since your input is on the od, as long as you can keep the speed up, it will have tremedous force at the axis, even though you arent expending as much force to keep the od in high speed rotation. Its all proportionate the the diameter, mass, speed of wheel, and diameters at which power is input and removed, plus any subsequent gearing, friction and load losses, more or less.
I said in an earlier post, depending on the flywheel it may be difficult to get it up to speed. I see that as an issue, but you could start it with a electric motor.
I have explained it the best I can. I'm sorry if that isnt good enough. If i am truly missing a simple engineering concept, I would appreciate an engineer educate me where I am incorrect.
We are certainly trying...
Would you accept that the flywheel performs the same function as a battery, that it stores energy in the form of motion, however it does not create or amplify any energy and cannot store more energy than what is put in to it by the cyclist?
Secondly would you concur that gearing will produce a change in speed of the drive tire of a bike given constant input speed by the cyclyst, but a 2x change in speed requires the cyclyst to pedal 2x harder?
In short, energy in minus losses = energy out. Discussing speed of the rotation of the flywheel and gearing of the bike is akin to debating 24v vs. 12v.
Really, the only question to answer here is if it makes any sense to use a human as the input. It is not that a flywheel or mechanical gearing have a bearing on the problem, rather if the meager amount of energy provided by the human legs can amount to anything useful other than spot jobs here and there. If you can put up a PV panel that can out-produce a human when the sun is out, isn't that a better solution? If so, perhaps a flywheel could store the energy from that array in place of a battery, in which case we are back on to the topic of the thread.
I think tension, inertia and gravitation (i.e. clockworks) would be an excellent "replacement" for many things that we currently use electricity for, and could allow us to continue using our RE energy even when it's not available... PV winds the clock during the day and then it ticks away all night. I'm sure there is some way to convert the output of clockworks back into electricity. The clockworks could be rigged up to crank a flashlight or radio, or even a small battery charger if you didn't have a full RE system. Historically, clockworks were used for all sorts of things besides clocks, from dolls to horseless carriages. DaVinci utilized clockworks of sorts in many of his inventions, relying on cogged gears, counterweights and tension bands of rope or sinew. I think that someone with a bit of mechanical savvy and a knack for invention could cobble together quite an effective little system, even one that could include some of the more modern marvels like LEDs and dynamos. But the first step would have to be determining exactly what needs actual electricity, and what would be better served with the mechanical energy instead... no sense using an electrical motor to do something that a mechanical engine would do almost as well (if not better).
One of the challenges of a large capacity deep cycle battery set up is the day to day operations to maintain a long service life. We had huge lead acid battery cells on the submarines I served on - each one was nearly 6 feet tall, and there were almost 120 cells. As you know there are a fixed number of discharge cycles in a lead acid PbSO4 battery. The recharging evolution is not a trivial event - very tight tolerances on individual cell temperature, specific gravity and H2 production, but are critical in ensuring the battery life is maintained and maximized.
Keeping a deep cycle batt on a voltage/current float will ensure power available when needed, but greatly reduces the life of the battery. Maintaining a battery on a float runs the risk of lead oxide forming and treeing across cell plates - and from personal experience, a cell reversal makes for an exciting time underwater.
You have to cycle the battery deeply to maximize it's useful life. We would run the battery down by maintaining a trickle discharge and charge it back up at periodic "amp-hours out" intervals.
Of course, we had 3600 KW steam driven electrical turbine generators feeding motor generator sets on each side of the battery as primary power sources that likely won't be available to the average joe post SHTF.
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